C带有一些限制的用户名的regex

在单个正则表达式中表达一组不相关的规则并不是很干净,但是可以通过使用lookaround断言来实现。 (Rubular) :

@"^(?=[A-Za-z0-9])(?!.*[._()\[\]-]{2})[A-Za-z0-9._()\[\]-]{3,15}$"

说明:

(?=[A-Za-z0-9])            Must start with a letter or number
(?!.*[._()\[\]-]{2})       Cannot contain two consecutive symbols
[A-Za-z0-9._()\[\]-]{3,15} Must consist of between 3 to 15 allowed characters

您可能需要考虑,这是否更容易阅读,更容易维护,作为一个简单的正则表达式列表,所有这些表达式必须成功验证,或者用普通的C代码编写。

作为对马克答案的优化:

^(?=.{3,15}$)([A-Za-z0-9][._()\[\]-]?)*$

说明:

(?=.{3,15}$)                   Must be 3-15 characters in the string
([A-Za-z0-9][._()\[\]-]?)*   The string is a sequence of alphanumerics,
                               each of which may be followed by a symbol

这一个允许Unicode字母数字:

^(?=.{3,15}$)((\p{L}|\p{N})[._()\[\]-]?)*$

这一个是Unicode变体,并且使用非捕获组:

^(?=.{3,15}$)(?:(?:\p{L}|\p{N})[._()\[\]-]?)*$